Sulfides and derivatives thereof as abscission agents

ABSTRACT

Fruit abscission is induced by application to a fruit bearing plant of particular sulfides and sulfide derivatives optionally in combination with non-phytotoxic surfactant different from said sulfides and derivatives. The sulfides and derivatives have the structural formula RXR&#39; wherein R&#39; is methyl or ethyl, wherein X is selected from the group consisting of sulfide, sulfoxide and sulfone, and R is akyl or alkenyl having 10-12 carbon atoms when X is sulfide or sulfoxide and 8-14 carbon atoms when X is sulfone.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation-in-part application of U.S. application Ser. No. 676,832, filed Apr. 14, 1976, entitled "SULFIDES AND DERIVATIVES THEREOF AS ABSCISSION AGENTS, now abandoned."

BACKGROUND OF THE INVENTION

This invention relates to application to fruit bearing plants of particular agents to induce fruit abscission. The invention is particularly useful where the fruits are citrus fruits, especially oranges.

The ability of plants to slough off organs, such as fruit, by an active separation of cells is described by plant physiologists as the process of abscission. Abscission, unaided by mechanical or chemical agents, results from the formation of a starch-filled layer of cells in the area of the fruit rind separating the stem from the fruit. This starch-filled layer is known as the abscission layer. Abscission occurs as the cells in the abscission layer begin to separate, eventually dropping the fruit from the stem. Abscission generally occurs shortly after the fruit has fully matured.

Commercial harvesting of fruit bearing plants very often requires deviation from the natural abscission cycle. Many varieties of fruit bearing plants, such as citrus, reach maturity and are harvested without completion of the abscission cycle. Moreover, citrus fruit can actually regreen, i.e., become more tightly attached to the fruit stem, as acceptable maturity standards for eating quality are reached.

When fruit is mechanically harvested without chemical aids and the cells of the abscission layer have not begun to separate or the fruit has begun to regreen, a great deal of force is required to remove the fruit. Often when adequate force to remove the fruit is applied to the fruit or fruit bearing plant, a break or tear can take place and a plug of tissue may be removed from the fruit rind; sometimes the fruit stem is broken, leaving a jagged woody stem attached to the fruit; or the fruit bearing plant itself is injured.

Several chemicals have been used to regulate the abscission process of fruit bearing plants in attempts to facilitate harvesting. Such chemicals are called, in general terms, harvesting aids or abscission agents. Typical abscission agents are formulated to loosen fruit at the time of harvest.

Abscission agents disclosed in the patent literature include pyridine-N-oxides (U.S. Pat. No. 3,810,752), alkylamines (U.S. Pat. No. 3,867,127), and hydroxylamines (U.S. Pat. No. 3,869,278).

Abscission agents that are the subject of pending patent applications are bis(2-pyridine-N-oxide)disulfides (Bednarz and Otten, Ser. No. 602,610 filed Aug. 7, 1975 now abandoned; bis(2-pyridine-N-oxide)disulfoxides (Otten and Rheinecker, Ser. No. 602,626 filed Aug. 7, 1975; bis(2-pyridine-N-oxide)disulfones (Otten and Rheinecker, Ser. No. 602,335 filed Aug. 6, 1975) now abandoned; and 1,2-bis(thiomethyl) alkanes and derivatives thereof (Rheinecker, Ser. No. 676,762, filed Apr. 14, 1976 now abandoned).

It is an object of the present invention to provide a method of inducing abscission utilizing agents of different chemical structure from the agents set forth above.

It is an object of this invention in one of its preferred aspects to provide a method of inducing abscission utilizing such agents in combination with non-phytotoxic surfactants.

It is an object of this invention in another of its preferred aspects to provide novel compositions for admixture with water for application to fruit bearing plants to induce fruit abscission.

These and other objects and advantages of the invention will be evident from the following detailed description.

DETAILED DESCRIPTION

The method of inducing fruit abscission of the present invention comprises applying to fruit bearing plants an effective amount of agent having the structural formula

    RXR'

wherein R' is methyl or ethyl, wherein X is selected from the group consisting of sulfide (i.e. -S-), sulfoxide ##STR1## and sulfone ##STR2## and R is alkyl or alkenyl having 10-12 carbon atoms where X is sulfide or sulfoxide and 8-14 carbon atoms when X is sulfone.

Specific examples of compounds useful within the scope of the invention and having the above structural formula where X is sulfide (referred to either as sulfides or as thioethers) are as follows: decyl methyl sulfide, ω-undecenyl methyl sulfide, 1- or 2-dodecenyl methyl sulfide, decyl ethyl sulfide, dodecyl ethyl sulfide and 1- or 2-dodecenyl ethyl sulfide.

Specific examples of compounds useful within the scope of the invention and having the above structural formula where X is sulfoxide are as follows: decyl methyl sulfoxide, ω-undecenyl methyl sulfoxide, dodecyl methyl sulfoxide, 1- or 2-decenyl methyl sulfoxide, and 1- or 2-dodecenyl methyl sulfoxide, decyl ethyl sulfoxide, dodecyl ethyl sulfoxide and 1- or 2-dodecenyl ethyl sulfoxide.

Specific examples of compounds useful within the scope of the invention and having the above structural formula wherein X is sulfone are as follows: octyl methyl sulfone, decyl methyl sulfone, dodecyl methyl sulfone, tetradecyl methyl sulfone, 1- or 2-octenyl methyl sulfone, 1- or 2-decenyl methyl sulfone, ω-undecenyl methyl sulfone, 1- or 2-dodecenyl methyl sulfone, 1- or 2-tetradecenyl methyl sulfone, octyl ethyl sulfone, decyl ethyl sulfone, dodecyl ethyl sulfone and 1- or 2-dodecenyl ethyl sulfone.

Preferred compounds for use within the scope of the present invention are decyl methyl sulfoxide, decyl methyl sulfone, 1-dodecenyl methyl sulfoxide and 1-dodecenyl methyl sulfone.

The most preferred compounds for use within the scope of the present invention are decyl methyl sulfoxide and 1-dodecenyl methyl sulfoxide.

The alkyl methyl or ethyl sulfide abscission agents described above are readily prepared, for example, by reacting the appropriate alpha olefin with methyl or ethyl mercaptan under pressure (such as 1000 psi) in the presence of 2, 2-azobis (2-methylpropionitrile), i.e. ABN. The alkenyl methyl or ethyl sulfide abscission agents described above with the double bond in the 1-position are readily prepared, for example, by reacting the appropriate 1-alkyne with methyl or ethyl mercaptan under pressure in the presence of ABN.

The sulfoxide abscission agents described above are readily prepared, for example, by oxidizing the appropriate sulfide (prepared, for example, by the method described in the above paragraph). This reaction can be carried out in dilute ethanol utilizing 30% hydrogen peroxide as an oxidizing agent.

The sulfone abscission agents described above are readily prepared, for example, by oxidizing the appropriate sulfide (prepared, for example, as described above) to the corresponding sulfoxide utilizing, for example, 30% hydrogen peroxide, and then oxidizing the sulfoxide to the corresponding sulfone utilizing, for example, additional 30% hydrogen peroxide. The sulfide can be oxidized directly to the sulfone by using a strong oxidizing agent such as sodium hypochlorite.

The alkenyl methyl or ethyl sulfide abscission agents previously described with the double bond in the 2-position are prepared, for example, by contacting the appropriate 1-alkenyl methyl or ethyl sulfide with a base, for example, potassium-t-butoxide in t-butyl alcohol, or sodium methoxide in methanol. Typically, the reaction results in a mixture of about 66% 2-position and 34% 1-position isomers.

The alkenyl methyl or ethyl sulfoxide abscission agents previously described with the double bond in the 2-position are prepared, for example, by contacting the appropriate 1-alkenyl methyl or ethyl sulfoxide with a base, for example potassium-t-butoxide in t-butyl alcohol, or sodium methoxide in methanol. Typically, the reaction results in a mixture of about 96% 2-position and 4% 1-position isomers.

The alkenyl methyl or ethyl sulfone abscission agents previously described with the double bond in the 2-position are prepared, for example, by contacting the appropriate 1-alkenyl methyl or ethyl sulfone, with a base, for example potassium t-butoxide in t-butyl alcohol or sodium methoxide in methanol. Typically the reaction results in a mixture of about 99% 2-position and 1% 1-position isomers.

As used hereinafter, the term "abscission agent(s)" refers only to the particular sulfide, sulfoxide and sulfone abscission agents described above with reference to the structural formula set forth above.

As indicated above, an effective amount of abscission agent is applied. This amount ordinarily ranges from about 0.1 pound per acre to 50 pounds per acre.

The abscission agents are preferably formulated into compositions for application. The agents which are normally liquids (for example, the sulfides and the alkenyl sulfoxides) are advantageously formulated as emulsions for example in water or other polar liquid. The agents which are normally solids (for example, the alkyl sulfoxides and the alkyl sulfones) are advantageously formulated as suspensions, for example in water or other polar liquid, or as solid compositions (dusts).

The formulations which are applied to fruit bearing plants within the scope of the present invention ordinarily contain from about 10 parts per million to about 10,000 prts per million of abscission agent.

The abscission agents are advantageously formulated for use within the scope of the present invention in admixture with non-phytotoxic, that is plant compatible surfactant, to provide either solid or liquid (including a suspension of a solid in a liquid phase) formulations. (The abscission agents herein can have surfactant properties; the surfactants referred to herein are different from the abscission agents used herein). The surfactants can have a positive effect on the inducing of abscission. Moreover, the surfactant acts as a dispersing or emulsifying agent if the combination of abscission agent and surfactant is admixed with water or other polar liquid for application to plants. In general, compositions for use within the scope of the method of the present invention or for admixture with water or other polar liquid for such use contain abscission agent and surfactant in a weight ratio of abscission agent to surfactant ranging from about 1:400 to about 10:1.

Surfactants for use as described above can be anionic, cationic, nonionic, ampholytic, and zwitterionic types.

Examples of suitable anionic surfactants for use herein are alkali metal (e.g. sodium), ammonium and amine salts of fatty alcohol sulfates having from 8-18 carbon atoms in the fatty chain and sodium salts of alkyl benzene sulfonates having from 9 to 15 carbon atoms in the alkyl chain.

Examples of suitable nonionic surfactants are the polyoxyethylene adducts of fatty alcohols having 10 to 18 carbon atoms and the polyethylene oxide condensates of alkyl phenols wherein the alkyl chain contains from about 6 to 12 carbon atoms and the amount of ethylene oxide condensed onto each mole of alkyl phenol is from about 5 to 25 moles, and the polyethylene oxide condensates of sorbitan esters (for example, surfactants sold under the tradename Tween) wherein the amount of ethylene oxide condensed onto each mole of sorbitan ester is about 10 to 40 moles.

Examples of suitable cationic surfactants are dimethyl dialkyl quaternary ammonium salts wherein the alkyl chains contain from about 8 to 18 carbon atoms and the salt forming anion is a halogen.

Examples of suitable ampholytic surfacants are derivatives of aliphatic secondary or tertiary amines in which one of the aliphatic substituents contains from about 8 to 18 carbon atoms and one contains an anionic water solubilizing group, e.g., sulfate or sulfonate. Specific suitable ampholytic surfactants are sodium-3-dodecylaminopropionate and sodium-3-dodecylaminopropane sulfonate.

Examples of suitable zwitterionic surfactants are derivatives of aliphatic quaternary ammonium compounds in which one of the aliphatic constituents contains from about 8 to 18 carbon atoms and one contains an anionic water solubilizing group. Specific examples of zwitterionic surfactants are 3-(N,N-dimethyl-N-hexadecylammonio)propane-1-sulfonate and 3-(N,N-dimethyl-N-hexadecylammonio)-2-hydroxypropane 1sulfonate.

Suitable surfactants besides those specifically described above are described in 37 Detergents and Emulsifiers - 1975 Annual", John W. McCutcheon, Inc.

Compositions for use within the scope of the present invention in liquid form (for example, for spraying on fruit bearing plants under superatmospheric pressure as aerosols or mists) are readily prepared for application by admixing abscission agent, surfactant (if used) and liquid carrier (water or other polar liquid) to form a stable emulsion or suspension with the concentration of abscission agent within the range as specified above and the weight ratio of abscission agent to surfactant within the range as specified above.

Compositions for admixture with water just prior to application are very desirable as these compositions are more economically packaged and shipped. Such compositions can be in the form of a solid (a wettable powder) or in the form of a liquid (suspension or emulsion) wherein the carrier is a minor proportion. These compositions preferably comprise (a) agent having the structural formula RXR' wherein R' is ethyl or methyl, wherein X is selected from the group consisting of sulfide, sulfoxide and sulfone, and R is alkyl or alkenyl having 10-12 carbon atoms when X is sulfide or sulfoxide and 8-14 carbon atoms when X is sulfone, (b) nonphytotoxic surfactant different from said RXR' (said surfactants being described in more detail above), -- the weight ratio of (a) to (b) ranging from about 1:400 to about 10:1; and (c) from 0% to abbout 20% by weight liquid carrier, preferably water.

Compositions for use in the form of dusts can be prepared by grinding or blending the solid abscission agents herein with a solid carrier such as talc, clay, silica, pyrophyllite or solid fertilizers. Annular compositions can be prepared by impregnating the abscission agents (dispersed or dissolved if normally solid) onto or into granulated carriers such as attapulgites or vermiculites, or granulated solid fertilizers.

The abscission agents herein are also advantageously used in plant-substantive formulations. The term "plant-substantive" is used herein to encompass formulations which mechanically or chemically adhere to the plant thereby resisting removal. Preferred materials suggested as plantsubstantive agents include various waxes and paraffins, polymers, and sulfur. Wax coated active can be prepared by dispersing the active ingredients in molten wax, forming the dispersion into small particles, and cooling the composition below the melting point of the wax. The water resistance of the particles can be controlled by increasing or decreasing the amount of wax employed so as to provide proper release for climatic conditions encountered. In areas of relatively heavy rainfall, the water resistance should normally be high and the amount of wax in the dispersion should be relatively high also. Conversely, in relatively dry areas the amount of wax should be relatively low. In addition, various additives can be dissolved in the wax phase in order to improve the water resistance of the composition or effect other benefits. U.S. Pat. No. 3,252,786, incorporated herein by reference, discloses the use of rosins or asphalts as effective slow-release additives. Other additives can be used, for example, to provide anticaking properties. Elemental sulfur is an essential plant nutrient in many areas. Thus, its use as a coating agent provides additional nutritive benefits. Sulfur coatings, however, tend to be very porous and present serious leaching problems. Therefore, sulfur-coated compositions usually contain a sealant material, for example petrolatum or waxes.

The compositions for use herein advantageously additionally include a safe and effective amount of other biologically active adjuvants. As used herein the term "biologically active adjuvant" includes insecticides, fungicides, herbicides, fertilizers, antimicrobial agents, and the like. The selection of adjuvants depends primarily upon the needs of the individual user. The preferred adjuvants for use herein are herbicides, insecticides, antimicrobial agents and fertilizers.

The above described invention is illustrated in the following specific examples. In each of the following examples I to X, the procedure was as follows: Abscission agent and surfactant were admixed with water to provide an aqueous formulation of 500 milliliters. This 500 milliliters of formulation was sprayed over an orange tree branch containing about 20 fruit. A week later, 10 fruit were removed from the treated branch with the stems still attached, and the force required to separate each of the fruit from the attached stem was measured utilizing a pull tester. An average force was calculated by adding up the forces of each of the 10 pulls and dividing by 10. Control tests were also carried out where no abscission agent was applied. In the control test where Valencia oranges were the subject of the test, unless otherwise stated, the average force required to pull each orange was about 20 pounds, and in the case of 30% of the oranges, rind was torn off as a result of the pull. In the control test where Hamlin oranges were the subject of the test, the average force required to pull each orange was about 12 pounds. The results in the examples below are compared to these control results to determine the magnitude of the effect of the abscission agent. In some cases in the examples below, the test results were that the fruit were too loose to pull (that is, the force required to remove the fruit was too small to measure), thereby demonstrating the maximum improvement within the framework of the test.

The following examples are illustrative of the scope of the invention and are not to be construed in any way as limiting the scope of the invention.

EXAMPLE I

A 500 milliliter aqueous formulation was made up utilizing 2 grams of octyl methyl sulfone (the above structural formula with X being sulfone, R being alkyl containing 8 carbon atoms and R' being methyl) and 5 grams of Surfactant X-77 (a mixture comprising alkylaryl polyoxyethylene glycols, free fatty acids and isopropanol - available from Colloidal Products Corporation). It was applied to Valencia oranges. The composition applied contained 4000 parts per million of abscission agent. The application of the 500 milliliters to one branch was equivalent to applying 16-32 pounds of abscission agent per acre. The average pull force determined was 9.9 pounds. In no case was the rind torn.

The above test was repeated. The fruit were too loose to pull.

Similar results are obtained when octyl ethyl sulfone is used in place of octyl methyl sulfone.

EXAMPLE II

A 500 milliliter agueous formulation was made up utilizing 2 grams of decyl methyl sulfide (the above structural formula with X being sulfide, R being alkyl containing 10 carbon atoms and R' being methyl) and 5 grams of Surfactant X-77. It was applied to Valencia oranges. The composition applied contained 4000 parts per million of abscission agent. The application of the 500 milliliters to one branch was equivalent to applying 16-32 pounds of abscission agent per acre. The average pull force determined was 10.5 pounds. In 10% of the cases (1 pull), the rind was torn in the pull.

Similar results are obtained when decyl ethyl sulfide is used instead of decyl methyl sulfide.

EXAMPLE III

A 500 milliliter aqueous formulation was made up utilizing 2 grams of decyl methyl sulfoxide (the above structural formula with X being sulfoxide, R being alkyl containing 10 carbon atoms and R' being methyl) and 5 grams of Surfactant X-77. It was applied to Valencia oranges. The composition applied contained 4000 parts per million of abscission agent. The application of the 500 milliliters to one branch was equivalent to applying 16-32 pounds of abscission agent per acre. The average pull force determined was 5.7 pounds. In no cases was the rind torn as a result of pulling the fruit.

The above test was repeated, and the average pull force was 9.8 pounds. In no cases was the rind torn as a result of pulling the fruit.

The above test was repeated again. The average pull force determined was 7.4 pounds. In 20% of the cases (2 pulls), the rind was torn as a result of pulling the fruit.

Similar results are obtained when decyl ethyl sulfoxide is used in place of decyl methyl sulfoxide.

EXAMPLE IV

A 500 milliliter aqueous formulation was made up utilizing 2 grams of decyl methyl sulfone (the above structural formula with X being sulfone, R being alkyl containing 10 carbon atoms and R' being methyl) and 5 grams of Surfactant X-77. It was applied to Valencia oranges. The composition applied contained 4000 parts per million abscission agent. The application of the 500 milliliters to one branch was equivalent to applying 16-32 pounds of abscission agent per acre. The average pull force determined was 8.3 pounds. In 30% of the cases (3 pulls) the rind was torn as a result of the pulls.

The above test was repeated. The average pull force determined was 7.6 pounds. The rind was torn in no cases as a result of pulling the fruit.

Similar results are obtained when decyl ethyl sulfone is used instead of decyl methyl sulfone.

EXAMPLE V

A 500 milliliter aqueous formulation was made up utilizing 2 grams of dodecyl methyl sulfide (the above structural formula with X being sulfide and R being alkyl containing 12 carbon atoms and R' being methyl) and 5 grams of Surfactant X-77. It was applied to Valencia oranges. The composition applied contained 4000 parts per million of abscission agent. The application of the 500 milliliters to one branch was equivalent to applying 16-32 pounds of abscission agent per acre. The fruit were too loose to pull. The test was repeated, and again the fruit were too loose to pull. The test was repeated, and again the fruit were too loose to pull.

Similar results are obtained when dodecyl ethyl sulfide is used instead of dodecyl methyl sulfide.

EXAMPLE VI

A 500 milliliter aqueous formulation was made up utilizing 2 grams of dodecyl methyl sulfoxide (the above structural formula with X being sulfoxide, R being alkyl containing 12 carbon atoms and R' being methyl) and 5 grams of Surfactant X-77. It was applied to Valencia oranges. The composition applied contained 4000 parts per million of abscission agent. The application of the 500 milliliters to one branch was equivalent to applying 16-32 pounds of abscission agent per acre. The average pull force determined was 8.1 pounds. In 20% of the cases (2 pulls), the rind was torn a a result of pulling fruit.

Similar results are obtained when dodecyl ethyl sulfoxide is used instead of dodecyl methyl sulfoxide.

EXAMPLE VII

A 500 milliliter aqueous formulation was made up utilizing 2 grams of dodecyl methyl sulfone (the above structural formula with X being sulfone, R being alkyl containing 12 carbon atoms and R' being methyl) and 5 grams of Surfactant X-77. It was applied to Valencia oranges. The composition applied contained 4000 parts per million of abscission agent. The application of the 500 milliliters to one branch was equivalent to applying 16-32 pounds of abscission agent per acre. The average pull force determined was 9 pounds. In 20% of the cases (2 pulls), the rind was torn as a result of pulling the fruit.

The above test was repeated. The averaage pull force determined was 9.6 pounds. In 40% of the cases (4 pulls), the rind was torn as a result of pulling the fruit.

Similar results are obtained when dodecyl ethyl sulfone is used instead of dodecyl methyl sulfone.

EXAMPLE VIII

A 500 milliliter aqueous formulation was made up utilizing 0.013 grams of 1-dodecenyl methyl sulfoxide (the above structural formula with X being sulfoxide, R being alkenyl containing 12 carbon atoms with the double bond being in the alpha, that is in the 1-position and R' being methyl) and 5 grams of Surfactant X-77. (This amounts to 25 parts per million of sulfoxide abscission agent.) It was applied to Valencia oranges. The application of the 500 milliliters to one branch was equivalent to applying 0.1 to 0.2 pounds of abscission agent per acre. The fruit were too loose to pull. The above test utilizing 25 parts per million abscission agent was repeated. The average pull force determined was 11.3 pounds. In 10% of the cases (1 pull), the rind was torn as a result of pulling the fruit.

The above test was repeated except that 0.025 grams of sulfoxide abscission agent was included in the formulation (50 parts per million). The application of the 500 milliliters to one branch was equivalent to applying 0.2-0.4 pounds of abscission agent per acre. The average pull force determined was 13.6 pounds. In 10% of the cases (1 pull), the rind was torn as a result of pulling the fruit.

The above test was repeated except that 0.038 grams of sulfoxide abscission agent was utilized in the formulation (75 parts per million). The application of the 500 milliliters to one branch was equivalent to applying 0.3-0.6 pounds of abscission agent per acre. The average pull force determined was 1.9 pounds. In no cases was the rind torn as a result of pulling the fruit. This test was repeated, and the fruit were too loose to pull.

The above testing was repeated utilizing sulfoxide active at levels in the formulation of 100 parts per million (equivalent to applying 0.4-0.8 pounds of abscission agent per acre), 200 parts per million (equivalent to applying 0.8-1.6 pounds of abscission agent per acre), 300 parts per million (equivalent to applying 1.2-2.4 pounds of abscission agent per acre), 500 parts per million (equivalent to applying 2.0-4.0 pounds per acre), and 1000 parts per million (equivalent to applying 4.0-8.0 pounds per acre). In all these cases, the fruit were too loose to pull.

The above testing was repeated except that the 1-dodecenyl methyl sulfoxide was used at a level of 500 parts per million and the surfactant was Triton X-100 (a polyethylene glycol alkyl aryl ether available from Rohm and Haas Company). The treated fruit were too loose to pull (in this case the control group required an average of 16 pounds pull force to remove the fruit from the stem).

Results similar to those obtained in the tests of this Example are obtained when 1-dodecenyl ethyl sulfoxide is used instead of 1-dodecenyl methyl sulfoxide.

EXAMPLE IX

A 500 milliliter aqueous formulation was made up utilizing 0.25 grams of 1-dodecenyl methyl sulfoxide (500 parts per million) and 5 grams of Surfactant X-77. It was applied to Hamlin oranges. The application of the 500 milliliters to one branch was equivalent to applying 2.0-4.0 pounds of abscission agent per acre. The fruit were too loose to pull.

Similar results are obtained when 1-dodecenyl ethyl sulfoxide is used instead of 1-dodecenyl methyl sulfoxide.

EXAMPLE X

A 500 milliliter aqueous formulation was made up utilizing 2 grams of 1-dodecenyl methyl sulfide (the above structural formula with X being sulfide, R being alkenyl containing 12 carbon atoms with the double bond being in the alpha, that is in the 1-position and R' being methyl) and 5 grams of Surfactant X-77. It was applied to Valencia oranges. The composition applied contained 4000 parts per million of abscission agent. The application of the 500 milliliters to one branch was equivalent to applying 16-32 pounds of abscission agent per acre. The treated fruit were too loose to pull. This test was repeated; the fruit were too loose to pull.

When in the above example, 2 grams of ω-undecenyl methyl or ethyl sulfide, ω-undecenyl methyl or ethyl sulfoxide, or ω-undecenyl methyl or ethyl sulfone is substituted for the 1-dodecenyl methyl sulfide, abscission activity is realized.

When in the above examples, the surfactant is omitted, abscission activity is still present.

When in the above examples, other surfactants are utilized instead of Surfactant X-77 and Triton X-100, such as sodium dodecyl benzene sulfonate, dimethyl didodecyl ammonium chloride, sodium-3-dodecylaminopropionate or 3-(N,N-dimethyl-N-hexadecylammonio)propane-1-sulfonate, equally good abscission results are obtained.

When in the above examples, the formulations are applied to other fruit bearing plants (for example to plants bearing citrus fruits such as lemons or grapefruit), abscission activity is realized.

The following examples illustrate compositions for admixture with water or other polar liquid just prior to use:

EXAMPLE XI

    ______________________________________                                                            parts by weight                                             ______________________________________                                         1-dodecenyl methyl sulfoxide                                                                        1                                                         Surfactant X-77      10                                                        ______________________________________                                    

    ______________________________________                                                            parts by weight                                             ______________________________________                                         1-dodecenyl ethyl sulfoxide                                                                         1                                                         Surfactant X-77      13.7                                                      Water                10                                                        ______________________________________                                    

EXAMPLE XIII

    ______________________________________                                                            parts by weight                                             ______________________________________                                         1-dodecenyl methyl sulfoxide                                                                        1                                                         Polyoxyethylene condensate of                                                                       10                                                        nonylphenol wherein the amount                                                 of ethylene oxide condensed on-                                                to each mole of nonylphenol is                                                 10 moles                                                                       Water                2                                                         ______________________________________                                    

    ______________________________________                                                            parts by weight                                             ______________________________________                                         Decyl ethyl sulfoxide                                                                               1                                                         Sodium dodecylbenzene sulfonate                                                                     21/2                                                      Water                0.5                                                       ______________________________________                                    

The term "fruit bearing plant" is used herein to include the major types of fruit, for example, berries such as grapes, tomatoes, blueberries, and oranges; drupes such as peaches, cherries, olives, plums and walnuts; aggregate fruits such as blackberries and raspberries; and multiple fruits such as pineapples, figs and mulberries; and accessory fruits such as apples, pears and strawberries. A thorough description of various other fruit bearing plants which may be treated in accordance with the present invention can be found in General Botany, Fuller and Richie, Barnes and Noble Inc. 1969, incorporated herein by reference.

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. In view of the variations that are readily understood to come within the limits of the invention, such limits are defined by the scope of the claims. 

What is claimed is:
 1. A method of inducing fruit abscission comprising applying to fruit bearing plants an effective amount of agent having the structural formula

    RXR'

wherein R' is selected from the group consisting of methyl and ethyl, wherein X is selected from the group consisting of sulfide, sulfoxide and sulfone; and R is alkyl or alkenyl having 10-12 carbon atoms when X is sulfide or sulfoxide and 8-14 carbon atoms when X is sulfone.
 2. The method of claim 1 wherein the structural formula is RXCH₃.
 3. The method of claim 2 wherein the agent applied is selected from the group consisting of decyl methyl sulfoxide, decyl methyl sulfone, 1-dodecenyl methyl sulfoxide and 1-dodecenyl methyl sulfone.
 4. The method of claim 3 wherein the agent applied is selected from the group consisting of decyl methyl sulfoxide, and decyl methyl sulfone.
 5. The method of claim 4 wherein the agent applied is decyl methyl sulfoxide.
 6. The method of claim 4 wherein the agent applied is selected from the group consisting of 1-dodecenyl methyl sulfoxide and 1-dodecenyl methyl sulfone.
 7. The method of claim 6 wherein the agent applied is 1-dodecenyl methyl sulfoxide.
 8. The method of claim 2 wherein said agent is applied in an amount in the range of about 0.1 to 50 lbs./acre.
 9. The method of claim 2 comprising also applying to the fruit bearing plant non-phytotoxic surfacant different from said RXR'.
 10. The method of claim 9 wherein the weight ratio o said RXCH₃ to surfactant ranges from about 1:400 to about 10:1.
 11. The method of claim 2 wherein the fruit is a citrus fruit.
 12. The method of claim 11 wherein the plants are orange trees. 